The overall objectives of this project are two-fold. First, experiments are described which should allow us to: a) physically map the six genes of Newcastle disease virus (NDV) and associate them with their specific mRNAs: b) in turn, to associate these with proteins for which they code; and c) identify the functions of these proteins. Second, experiments are described with the related goals of: a) elucidating the mechanism of inhibition of host cell protein synthesis and the accompanying replacement by viral protein synthesis; b) relating these to cell killing; and c) determining the relationships between these phenomena and/or viral glycoprotein cleavage or synthesis and cytopathogenesis. Methods include: l) biochemical mapping procedures; 2) in vitro transcription; 3) cell free translation; and 4) the assays for various biochemical and biological proper ties of virions and infected cells. The former studies will employ our well characterized Australia Victoria strain as well as our temperature-sensitive mutants of this strain. The latter studies will also employ these ts mutants as well as a series of non-conditional, non-cytopathic mutants, and conditionally cytopathic mutants, and several naturally occurring avirulent strains.